Wire bonding is a method of making electrical interconnections among bonding pads, such as those located on an integrated circuit (IC) device and/or a printed circuit board (PCB) during semiconductor and/or storage device fabrication. Further, wire bonding can be used to connect an IC to other electronics or to connect from one PCB to another. Wire bonding is generally considered a cost-effective and flexible interconnect technology, which is used to assemble a wide variety of semiconductor packages. There are two main classes of wire bonding, wedge bonding and ball bonding. Both wedge bonding and ball bonding are typically accomplished using a combination of heat, compressive force, and ultrasonic energy to bond a wire to one or more bonding pads.
Wedge bonding is typically carried out at room temperature, but has several limitations. First, the take-off angle and direction are substantially limited. Second, the wedge bond creates a relatively large foot size. Third, additional wedge bonds may not be stacked on top of a previous bonded spot on a bonding pad. As a result, wedge bonding is not an available options in applications with very small bonding pads or when an extruded object is in front of the take-off direction of the wedge bonded wire. Further, the bonded spot may not be reused due to oxidation (e.g., when an aluminum alloy wire is used), which could become a problem when the size of the bonding pad size is small and rewiring is necessary.
As distinct from wedge bonding, ball bonding typically heats the bonding pad to create the bond. However, heating the bonding pad may not be an available option due to the heat potentially damaging sensitive IC devices adjacent the bonding pad or other components of the IC (e.g., adhesives). Ball bonding has several advantages over the wedge bond, such as more flexibility in take-off direction and angle from the bonding pad without inducing unacceptable stresses on the bond, greatly reduced bonding size, and ball-on-ball stacking capability.